1 H and 13 C NMR study of phosphopeptides: 2 —Ac–PSer–Gly, Ala–PSer–Gly and Gly–PSer–Phe

1 H and 13 C NMR spectra of AC–PSer–Gly, Ala–PSer–Gly and Gly–PSer–Phe have been measured and analysed as a function of pD. The NMR parameters of the PSeryl side chain are a function of the sequence. The second titration step of the phosphate group (p K 2 = 5.7) is much more difficult to detect in Ac–PSer–Gly and Ala–PSer–Gly than in Gly–PSer–Phe. The conformation in which H‐αC‐αC‐βOP forms a planar W‐type arrangement predominates only for Ala–PSer–Gly. In the other two phosphopeptides the gauche conformations contribute increasingly, in particular for Gly–PSer–Phe.